示例 Product 表结构: 示例 Product 表数据: 想要的效果是,以 GroupName 字段分组,取出分组中通过 Sort 降序最新的数据,通过示例数据,可以推算出结果数据的 ID 应该为:7.5.3. 示例 SQL 代码: select * from Product p where ID=(select top 1 ID from Product where p.GroupName=GroupName order by Sort desc) order by Sort desc
[sql]mysql管理手头手册,多对多sql逻辑 国家--城市例子 class Country(models.Model): name = models.CharField(max_length=30) def __str__(self): return self.name class City(models.Model): country = models.ForeignKey(Country, on_delete=models.CASCADE) name = models.CharFiel
语法格式:row_number() over(partition by 分组列 order by 排序列 desc) 一个很简单的例子 1,先做好准备 create table test1( id varchar(4) not null, name varchar(10) null, age varchar(10) null ); select * from test1; insert into test1(id,name,age) values(1,'a',10); insert into t
Get请求: public static Result<GetExpressCollectionResponseType> GetDataFromWebs(string waybillNumbers) { var result = new Result<GetExpressCollectionResponseType>(); try { var url = "http://***.com.cn/service/Manage/999001/Expresses/GetExpr
addtime='2016-09-03 18:12:44' substr(addtime,1,10) as 创建日期 SUBSTR(string, string charcter, number of charcters)参数含义:string:为字符列或字符串表达式string charcter:子串的起始位置number of charcters:返回字符的个数